Programmable audio/video encoding system capable of downloading compression software from DVD disk

ABSTRACT

A programmable audio/video encoder capable of receiving an encoding algorithm from an external digital information source. In one embodiment, the system accepts recordable DVD disks having a read-only sector for storing customized video encoding algorithms and programs the programmable video encoder with the customized video encoding algorithms prior to encoding and recording a video signal on the disk. By designing the video encoding algorithms to optimize one or more of a number of desirable attributes, the DVD media vendors can then create “classes” of recordable DVD disks, i.e. high capacity, high quality, high speed, high image detail, high color resolution, variable frame rate, etc. One programmable video encoder for this embodiment would include an instruction memory for storing the customized video algorithms, a video buffer for buffering the video signal, and a CPU which encodes the video signal according to the customized video algorithms.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of video compression systems, and inparticular to programmable DVD video encoders.

2. Description of the Related Art

A video program signal is converted to a digital format, and thencompressed and encoded in accordance with one of several knowncompression algorithms or methodologies. This compressed digital systemsignal, or bitstream, which includes a video portion, an audio portion,and other informational portion, is then transmitted to a receiver.Transmission may be over existing television channels, cable televisionchannels, satellite communications channels, and the like. A decoder isthen typically employed at the receiver to decompress and decode thereceived system signal in accordance with the same compression algorithmused to encode the signal. The decoded video information may then beoutput to a display device, such as a television (TV) monitor.

Video compression and encoding is typically performed by a videoencoder. The video encoder normally produces a compressed digital systemsignal that conforms to a recognized standard or specification agreed toamong the senders and receivers of digital video signals. One suchstandard is DVD. It includes audio and video compression technologies,as well as provisions for other information streams. The videocompression standard adopted by DVD was developed by the Moving PicturesExperts Group (MPEG). The MPEG standard concerns high-quality coding ofpossibly interlaced video, including high definition television (HDTV).A wide range of applications, bit rates, resolutions, signal qualitiesand services are addressed, including all forms of digital storagemedia, TV broadcasting and communications.

The MPEG standard, although it details the structure and syntax of thecompressed bitstreams, does not provide complete system specifications.A nearly infinite number of bitstreams can be generated to represent animage sequence while conforming to the MPEG standard. Designconsiderations such as image preprocessing, motion estimation methods,the order of compressed frame types, bit-rate management, implementationcomplexity, coded image size, color space sampling, and fieldinterleaving, all lead to different representations of the same image.It should be recognized that the different representations may havevarying degrees of quality, both in terms of compression and accuracy,but they all conform to the MPEG standard. A somewhat lesser degree offreedom exists in the way a bitstream is decoded, but neverthelessexists. For example, note that some video degradation might be anacceptable tradeoff for reduced implementation complexity, or that thecoded image characteristics (size, frame rate) might be incompatiblewith the display device and require some adjustments (scaling,pulldown). The MPEG standard carefully avoids addressing issues such asthese, preferring instead to allow industries to “customize” encoder anddecoder implementations to their best advantage.

Currently, the customization of the encoder and decoder implementationsis performed by the system designers, primarily with a combination ofhardware and proprietary microcode, and the displayed image qualitythereby determined. One drawback of this approach is that the digitalmedia vendors cannot easily “improve” image quality to distinguishthemselves from their competitors, nor can they easily upgrade theirsystems to incorporate the latest compression advances. It is desirableto provide a method for DVD media vendors to participate in the encoderand decoder customization process to produce media classes that providefor optimized trade-offs (e.g. capacity vs. image quality), and in sodoing provide better performances for specific applications.

SUMMARY OF THE INVENTION

The problems outlined above are in large part solved by a digitalaudio/video recording system having a programmable video encoder capableof receiving an encoding algorithm from an external source. In oneembodiment, the system accepts recordable DVD disks having a read-onlysector for storing customized video encoding algorithms and programs theprogrammable video encoder with the customized video encoding algorithmsprior to encoding and recording a video signal on the disk. By designingthe video encoding algorithms to optimize one or more of a number ofdesirable attributes, the DVD media vendors can then create “classes” ofrecordable DVD disks, i.e. high capacity, high quality, high speed, highimage detail, high color resolution, variable frame rate, etc. Oneprogrammable video encoder for this embodiment would include aninstruction memory for storing the customized video algorithms, a videobuffer for buffering the video signal, and a CPU which encodes the videosignal according to the customized video algorithms. In a secondembodiment, the system accepts CD-ROM disks having customizedaudio/video algorithms and automatically downloads the customizedalgorithms to use for encoding and recording digital audio/videosignals.

Broadly speaking, the present invention contemplates a programmablevideo encoding system comprising a read head, a video encoder, and achannel coding and modulation circuit. The read head is configured toread a video encoding algorithm from a read-only sector on a digitalinformation storage medium. The video encoder is operatively coupled tothe read head to receive and store the video encoding algorithm. Thevideo encoder is configured to receive a video signal and configured toexecute the video encoding algorithm on the received video signal toproduce an encoded digital video signal. The channel coding andmodulation circuit is operatively coupled to receive the encoded digitalvideo signal and configured to convert the encoded digital video signalinto a modulated digital signal. The video encoder may include aninstruction memory, a video buffer, and a CPU. The system may beconfigured to read and execute the video encoding algorithm from theread-only sector of the digital information storage medium every timethe digital information storage medium is engaged in an operativerelationship with the read head. The system may also include a recordhead operatively coupled to the channel coding and modulation circuit toreceive the modulated digital signal and configured to record themodulated digital signal on a recordable digital information storagemedium.

The present invention further contemplates a method for recording adigital video program of a predetermined caliber. The method comprises:(i) creating a recordable digital information storage medium with aread-only sector; (ii) storing a video encoding algorithm in theread-only sector; and (iii) placing the recordable digital informationstorage medium in a video recording system. The video encoding algorithmis designed to yield recordings of the predetermined caliber. The methodmay further comprise: (iv) reading the video encoding algorithm; (v)receiving a video signal; (vi) executing the encoding algorithm toconvert the video signal into an encoded digital signal; and (vii)recording the encoded digital signal in the recordable digitalinformation storage medium.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to theaccompanying drawings in which:

FIG. 1 is a block diagram of a programmable digital video record andplayback system; and

FIG. 2 is a block diagram of a programmable digital video encoder.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Itshould be understood, however, that the drawings and detaileddescription thereto are not intended to limit the invention to theparticular form disclosed, but on the contrary, the intention is tocover all modifications, equivalents and alternatives falling within thespirit and scope of the present invention as defined by the appendedclaims.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to the figures, FIG. 1 provides a block diagram of aprogrammable digital video record and playback system which can acceptrecordable DVD disks having a read-only sector with a video encodingalgorithm. The system is configured to read the video encoding algorithmand execute the algorithm when encoding video signals for storage on therecordable DVD disks. This system allows for the use of various classesof recordable DVD disks in which each class is targeted for recordingdigital video signals of a given type (i.e. long play, high resolution,superior color, etc.)

The system receives audio and digital signals which are converted todigital signals by analog-to-digital (A/D) converters 102 and 104. Thedigital signals are encoded by a DVD encoder 106 which uses synchronousdynamic random access memory (SDRAM) 108 as a frame store buffer. Theencoded digital signals are processed by an error correction encoder 110then converted to a modulated digital signal by modulator 112. Themodulated digital signal is coupled to a digital signal processor (DSP)114 and from there to a power amplifier 116. Amplified signals arecoupled to drive motors 118 to spin a recordable DVD disk 120 and arecord head 122 to store the modulated digital signal on the recordableDVD disk 120. Stored data can be read from the recordable DVD disk 120by read head 124 which sends a read signal to DSP 114 for filtering. Thefiltered signal is coupled to channel control buffer 126 for ratecontrol, then demodulated by demodulator 128. An error correction codedecoder 130 converts the demodulated signal into either a video encodingalgorithm for DVD encoder 106, or an encoded video signal which is thendecoded by DVD decoder 134 and converted to analog audio and videosignals by digital-to-analog (D/A) converters 136 and 138. Amicrocontroller 132 coordinates the operations of the system componentsand loads the video encoding algorithm into the DVD encoder 106.

A/D converter 102 operates to convert an analog video signal into adigital video signal. This is likely to be the case for an analog videocamera or videocassette playback recording. Digital cameras and computergenerated graphics produce digital video signals. If a digital videosignal is being received, the A/D converter 102 may be bypassed.Similarly, A/D converter 104 operates to convert an analog audio signalinto a digital audio signal. Microphones and analog TV broadcasts aresources of analog audio signals. Examples of digital audio sources arecompact disks and digital audio cassettes. For digital audio sources,the AID converter 104 may be bypassed.

DVD encoder 106 operates to encode the digital audio and video signalsto produce an encoded digital signal. DVD encoder 106 is preferably aprogrammable encoder able to execute software video encoding algorithms.The operation and structure of the DVD encoder 106 is discussed furtherbelow.

Error correction encoder 110 and modulator 112 operate to providechannel coding and modulation for the encoded digital signal. Errorcorrection encoder 110 may be a Reed-Solomon block code encoder, whichprovides protection against errors in the read signal. The modulator 112converts the error correction coded output into a modulated signalsuitable for recording on DVD disk 120.

DSP 114 serves multiple functions. It provides filtering operations forwrite and read signals, and it acts as a controller for the read/writecomponents of the system. The modulated signal provided by modulator 112provides an “ideal” which the read signal should approximate. In orderto most closely approximate this ideal, certain nonlinearcharacteristics of the recording process must often be compensated. TheDSP 114 may accomplish this compensation by pre-processing the modulatedsignal and/or post-processing the read signal. The DSP 114 controls thedrive motors 118 and the record head 122 via the power amplifier 116 torecord the modulated signal on the DVD disk 120. The DSP 114 alsocontrols the drive motors 119 and uses the read head 124 to scan the DVDdisk 120 and produce a read signal.

The channel control buffer 126 provides buffering of the read signal,while demodulator 128 demodulates the read signal and error correctioncode decoder 130 decodes the demodulated signal. After decoding thedemodulated signal, the error correction decoder 130 forwards thedecoded signal in response to the microcontroller 132. If themicrocontroller 132 indicates that the output is a video encodingalgorithm, the output is forwarded to the microcontroller 132 for use inthe DVD encoder 106. Otherwise the output is assumed to be an encodeddigital signal and is forwarded to DVD decoder 134.

DVD decoder 134 operates to decode the encoded digital signal to producedigital audio and video signals. The operation and structure of DVDdecoder 134 are discussed further below. The digital audio signal may beconverted to an analog audio signal by D/A converter 136, and thedigital video signal may be converted to an analog video signal by D/Aconverter 138. One specific instance of D/A converter 138 is a NTSC(National Television Standards Committee) standard or a PAL (PhaseAlternation Line) standard encoder which converts the digital videosignal into a raster scan signal for display on a monitor.

Turning now to FIG. 2, a block diagram of a programmable DVD videoencoder 106 is shown. The digital audio signal may be compressed by oneof three audio compression blocks: a MUSICAM encoder 202, a Dolbydigital (AC3) encoder 204, or a Linear PCM encoder 206. A specialpurpose RISC CPU 210 accesses the appropriate audio encoder hardware tochoose the audio compression method. The RISC CPU 210 operates onsoftware stored in instruction memory 212, which can be loaded bymicrocontroller 132 via instruction interface 211. A video buffer 214buffers the digital video signal while the RISC CPU 210 operates toconvert the digital video signal into a compressed video signal to becombined with the compressed audio signal to form the encoded digitalsignal bitstream. A bitstream buffer 216 is used to buffer the encodeddigital signal until it can be processed by the error correction encoder110. The video compression process requires the use of frame buffers,and RISC CPU 210 uses SDRAM 108 via SDRAM interface 218 for thispurpose.

In one embodiment, RISC CPU 210 relies on supporting video encodinghardware 208 to perform the low-level steps of the video encodingalgorithm such as motion compensation and discrete cosine transform ofmacroblocks. The video encoding hardware 208 may be programmable viaconfiguration registers to set the desired method of operation. Theaudio encoders 202, 204, and 206 may also be programmable and used in asupporting role. In this case, the RISC CPU 210 can also provide thehigh-level aspects of the audio compression algorithm. The steps offorming the bitstream syntax and interleaving the audio and videoprograms are performed by the RISC CPU 210.

RISC CPU 210, perhaps along with the supporting audio and video encodinghardware 208, compresses the audio and video signals using a softwarealgorithm stored in instruction memory 212. The software algorithm maycome from a variety of sources, including a system EEPROM. Inparticular, the software algorithm may be provided in a read-only sectoron a recordable DVD disk 120. In one embodiment, the insertion of arecordable DVD disk 120 initiates a load sequence in which the softwarealgorithm is read from the read-only sector of the recordable DVD disk120 and stored in instruction memory 212. A subsequent initiation of arecord sequence causes the system to use the loaded software algorithmfor compressing any audio/video program it records on the recordable DVDdisk 120.

To highlight customizable aspects of the video compression algorithmwhich the RISC CPU 210 executes, a general discussion of the steps whichmight be performed by a video MPEG encoder is now provided.

In order to compress a video signal, it is typically necessary to samplethe analog data and represent this data with digital values of luminanceand color difference. Video input is typically sampled at 4:2:2, where ared color difference signal (Cr) and a blue color difference signal (Cb)are sub-sampled 2-to-1 with respect to a luminance (Y) signal. The MPEGstandard suggests that the luminance component Y of a video signal maybe sampled with respect to the color difference signals Cr, Cb by aratio of 4-to-1. That is, for every four samples of the luminancecomponent Y, there is one sub-sample each of the color differencecomponents Cr and Cb. A 4-to-1 sampling ratio is generally consideredacceptable because the human eye is much more sensitive to luminance(brightness) components than to color components. For end users, videosub-sampling typically is performed 2-to-1 in both the vertical andhorizontal directions (known as 4:2:0). However, the MPEG standardallows the use of other sampling ratios, and commercial studio-qualitysystems will often not vertically sub-sample the color differencecomponents at all, i.e. maintain 2-to-1 horizontal only sampling ratios.A 3-to-2 sampling ratio has also been discussed for use in MPEG videocompression.

Once the video signal is sampled, it is typically formatted into anon-interlaced signal that contains all of the picture content. Moreparticularly, the video signal includes a plurality of pictures orframes, where each frame includes a plurality of horizontal scan linesfor display. An interlaced signal, in contrast, is one that containsonly part of the picture content for each complete display scan. In aninterlaced signal, each frame is divided into two fields. The two fieldsare often referred to as the even and odd or the top and bottom fields.Each field spans the length of the frame, but only includes every otherscan line. The purpose for such field division is that most TVs todaydisplay the video information in interlaced format, by displaying onefield first, such as the entire top field, then displaying the entirebottom field. Note that although the non-interlaced frame format iscommon, interlaced field encoding is permitted under the MPEG-2standard. It is possible that the interlaced field encoding may be moresuitable for use with some low-cost video cameras.

After a video signal is sampled and formatted, the encoder may processit further by converting it to a different resolution in accordance withthe image area to be displayed. A wide variety of picture resolutionsare available, but a higher encoded resolution typically implies ahigher bit rate and hence a smaller disk capacity.

The video encoder must next determine how to encode each picture. Apicture may be considered as corresponding to a single frame of motionvideo, or to a single frame of a movie film. Different encoding schemesmay be employed for each picture. The most prevalent picture codingtypes are: I-pictures (intra-coded pictures) which are coded withoutreference to any other pictures and are often referred to as anchorframes; P-pictures (predictive-coded pictures) which are coded usingmotion-compensated prediction from the past I- or P-reference picture,and may also be considered anchor frames; and B-pictures(bidirectionally predictive-coded pictures) which are coded using motioncompensation from a previous and a future I- or P-picture. These picturetypes will be referred to as I, P or B frames.

A typical coding scheme may employ a mixture of I, P, and B frames.Typically, an I frame may occur every half a second, with two B framesinserted between each pair of I or P frames. I frames provide randomaccess points within the coded sequence of pictures where decoding canbegin, but are coded with only a moderate degree of compression. Pframes are coded more efficiently using motion compensated predictionfrom a past I or P frame and are generally used as a reference forfurther prediction. B frames provide the highest degree of compressionbut require both past and future reference pictures for motioncompensation. B frames are not used as references for prediction. Theorganization of the three picture types in a particular video sequenceis very flexible. A fourth picture type is defined by the MPEG standardas a D-picture, or DC-picture, which is provided to allow a simple, butlimited quality, Fast-Forward mode. Note that the mixture of frames iscustomizable, and that some higher compression may be attained byreducing the number of random-entry points in the bitstream. Conversely,better slow and fast, forward and reverse motion effects may be providedby sacrificing some compression and increasing the number of randomentry point in the bitstream.

Once the picture types have been defined, the encoder may estimatemotion vectors for each 16 by 16 macroblock in a picture. A macroblock(MB) is the basic coding unit for the MPEG standard. A macroblockconsists of a 16-pixel by 16-line portion, or four 8-pixel by 8-lineblocks, of luminance components (Y) and several spatially corresponding8 by 8 blocks of chrominance components Cr and Cb. The number of blocksof chrominance values depends upon which particular format is used.Common color space sampling schemes include 4:4:4 for maximum qualitybut relatively low compression, 4:2:2 including two Cb chrominanceblocks and Cr chrominance blocks, and 4:2:0 including one Cb chrominanceblock and one Cr chrominance block. A plurality of such macroblocks forma horizontal slice within a frame, where the slice is the basicprocessing unit in an MPEG coding scheme. A plurality of such slicesform each picture or frame, which is the basic unit of display. Asdescribed previously, however, each frame is typically interlaced anddisplayed as two separate fields.

Motion vectors provide displacement information between a currentpicture and a previously stored picture. P frames use motioncompensation to exploit temporal redundancy, or lack of substantialchanges, between picture frames in the video. Apparent motion betweensequential pictures is caused by pixels in a previous picture occupyingdifferent positions with respect to the pixels in a current macroblock.This displacement between pixels in a previous and a current macroblockis represented by motion vectors encoded in the MPEG bitstream.Typically, the encoder chooses which picture type is to be used for eachgiven frame. Having defined the picture type, the encoder then estimatesmotion vectors for each macroblock in the picture. Typically in Pframes, one vector is employed for each macroblock, and in B frames, oneor two vectors are used. Note that the algorithm for determining motionvectors is completely customizable, and that “good” motion vectorestimation is largely a matter of judgment. Different motion estimationtechniques may be more suitable (i.e. result in better compression) fordifferent film types (e.g. cartoons vs. action movies).

When the encoder processes B frames, it usually re-orders the picturesequence so that a video decoder receiving the digital video signaloperates properly. Since B frames are usually coded using motioncompensation based on previously sent I or P frames, the B frames canonly be decoded after the subsequent anchor pictures (an I or P frame)have been received and decoded. Thus, the sequence of the series ofpictures may be re-ordered by the encoder so that the pictures arrive atthe decoder in a proper sequence for decoding of the video signal. Thedecoder may then re-order the pictures in proper sequence for viewing.

For a given macroblock of video data, the encoder is programmed toselect a coding mode depending on the picture type, the effectiveness ofmotion compensation in the particular region of the picture, and thenature of the signal within the block. The criteria for making thisselection are customizable. A coding method is selected, and the encoderbegins to process the macroblocks accordingly. For I frames, the encoderperforms a Discrete Cosine Transform (DCT) on the current macroblock.For P and B frames, the encoder first performs a motion-compensatedprediction of the block contents based on past and/or future referencepictures. The encoder then produces an error signal by subtracting theprediction from the actual data in the current macroblock. The errorsignal is similarly separated into 8 by 8 blocks (four luminance blocksand two chrominance blocks for 4:2:0 encoding). A DCT is then performedon each block to achieve further compression. The DCT operation convertsan 8 by 8 block of pixel values to an 8 by 8 matrix of horizontal andvertical coefficients of spatial frequency. An 8 by 8 block of pixelvalues can subsequently be reconstructed by a video decoder performingan Inverse DCT (IDCT) on the spatial frequency coefficients.

In addition to the signal compression that is achieved by the encodingprocess itself, a substantial degree of intentional (but lossy) signalcompression can be achieved by a process of selecting a quantizationstep size, where the quantization intervals or steps are identified byan index. Considerable freedom is permitted in making the selection ofquantization step sizes. The quantization level of frequencycoefficients corresponding to the higher spatial frequencies favors thecreation of coefficient values of zero by choosing an appropriatequantization step size based on the human visual perception system. Inparticular, the step size is chosen so that the human visual perceptionsystem is unlikely to notice the loss of a particular spatial frequencyunless the coefficient value for that spatial frequency rises above theparticular quantization level. The statistical encoding of the resultingruns of consecutive zeroed-valued coefficients corresponding to thehigher-order coefficients accounts for considerable compression gain.Higher quantization values allow greater compression at the expense ofquality, while lower values allow higher video quality at the expense ofmore bits.

In order to cluster non-zero coefficients early in the series and toencode as many zero coefficients as possible following the last non-zerocoefficient in the ordering, the coefficient sequence is often organizedin a specified orientation termed zigzag ordering. More than one methodof zigzag ordering is possible. Zigzag ordering concentrates the highest(and least common) spatial frequencies at the end of the series. Oncethe zigzag ordering has been performed, the encoder performs “run-lengthcoding” on the AC coefficients. This process reduces each 8 by 8 blockof DCT coefficients to a number of events represented by a non-zerocoefficient and the number of preceding zero coefficients. Because thehigh-frequency coefficients are more likely to be zero, the combinationof zigzagging and run-length coding results in additional videocompression.

The video encoder then performs variable-length coding (VLC) on theresulting data. VLC is a reversible lossless procedure for coding datathat assigns shorter code words to frequent events and longer code wordsto less frequent events, thereby achieving additional video compression.Huffman encoding is a particularly well-known form of VLC that reducesthe number of bits necessary to represent a data set without losing anyinformation.

The final compressed video data is then ready to be transmitted to astorage device or over a transmission medium for reception anddecompression by a remotely located decoder. The MPEG standard specifiesa particular syntax for a compressed bitstream, and bitstreams whichadhere to this standard can be decoded by MPEG-compliant decoders.

The video decoding process is generally the inverse of the videoencoding process and is employed to reconstruct a motion picturesequence from a compressed and encoded bitstream. The data in thebitstream is decoded according to a syntax that is itself defined by thedata compression algorithm. The decoder must first identify thebeginning of a coded picture, identify the type of picture, then decodeeach individual macroblock within a particular picture. If there aremotion vectors and macroblock types (each of the frame types I, P, and Bhave their own macroblock types) present in the bitstream, they can beused to construct a prediction of the current macroblock based on pastand future reference frames that the decoder has already stored. TheHuffman coded data are decoded and inverse zigzagged back intocoefficient data. The coefficient data is then inverse quantized andoperated on by an IDCT (inverse DCT) process so as to transform themacroblock data from the frequency domain to data in the time and spacedomain.

After all of the macroblocks have been processed by the decoder, thepicture reconstruction is complete. If a reconstructed frame is areference or anchor frame, such as an I or a P frame, it replaces theoldest stored anchor frame and is used as the new anchor for subsequentframes. As noted above, the frames may also need to be re-ordered beforethey are displayed in accordance with their display order instead oftheir coding order. After the frames are reordered, they may then bedisplayed on an appropriate display device.

The use of various algorithm sources other than a read-only sector on arecordable disk are contemplated. A separate, dedicated “algorithm disk”may be placed into the system and the encoding algorithms retrieved fromit before the system records the on the recordable digital media. Thesystem may be coupled to the internet to download customized encodingalgorithms, or may be part of a set-top box coupled to receive digitaltelevision transmissions and configured to detect and download encodingalgorithms provided as part of the transmission. Hence the encodingalgorithms may be provided to the system via satellite or cable.

Numerous other variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.For example, other customizable video encoding standards may be used,e.g. H.261, H.263, JPEG, and/or proprietary encoding methods, and use ofthese is contemplated. It is intended that the following claims beinterpreted to embrace all such variations and modifications.

What is claimed is:
 1. A programmable video encoding system comprising:a read head configured to read a video encoding algorithm from aread-only sector on a digital information storage medium; a videoencoder operatively coupled to the read head to receive and store thevideo encoding algorithm, wherein the video encoder is configured toreceive a video signal, and wherein the video encoder is configured toexecute the video encoding algorithm on the received video signal toproduce an encoded digital video signal; and a channel coding andmodulation circuit operatively coupled to receive the encoded digitalvideo signal and configured to convert the encoded digital video signalinto a modulated digital signal, wherein the system is configured toread and execute the video encoding algorithm from the read-only sectorof the digital information storage medium every time the digitalinformation storage medium is configured in an operative relationshipwith the read head.
 2. The programmable digital video recording systemof claim 1, wherein the video encoder includes: an instruction memorycoupled to receive and store the video encoding algorithm; a videobuffer coupled to receive and store the video signal; and a CPU coupledto the instruction memory to retrieve instructions and coupled to thevideo buffer to retrieve the video signal, wherein the CPU is configuredto execute the video encoding algorithm on the video signal.
 3. Theprogrammable digital video recording system of claim 1, wherein thesystem is configured to read and execute the video encoding algorithmfrom the read-only sector of the recordable digital information storagemedium every time the recordable digital information storage medium isconfigured in an operative relationship with the read and record heads.4. The programmable digital video recording system of claim 1, whereinthe channel coding and modulation circuit includes: an error correctionencoder coupled to receive the encoded digital video signal andconfigured to convert the encoded digital video signal to an errorcorrection coded signal; and a modulator coupled to the error correctionencoder to receive the error correction coded signal, wherein themodulator is configured to convert the error correction coded signalinto the modulated digital signal.
 5. A programmable video encodingsystem comprising: a read head configured to read a video encodingalgorithm from a read-only sector on a digital information storagemedium; a video encoder operatively coupled to the read head to receiveand store the video encoding algorithm, wherein the video encoder isconfigured to receive a video signal, and wherein the video encoder isconfigured to execute the video encoding algorithm on the received videosignal to produce an encoded digital video signal; and a channel codingand modulation circuit operatively coupled to receive the encodeddigital video signal and configured to convert the encoded digital videosignal into a modulated digital signal.
 6. The programmable videoencoding system of claim 5, wherein the video encoder includes: aninstruction memory coupled to receive and store the video encodingalgorithm; a video buffer coupled to receive and store the video signal;and a CPU coupled to the instruction memory to retrieve instructions andcoupled to the video buffer to retrieve the video signal, wherein theCPU is configured to execute the video encoding algorithm on the videosignal.
 7. The programmable video encoding system of claim 5, whereinthe channel coding and modulation circuit includes: an error correctionencoder coupled to receive the encoded digital video signal andconfigured to convert the encoded digital video signal to an errorcorrection coded signal; and a modulator coupled to the error correctionencoder to receive the error correction coded signal, wherein themodulator is configured to convert the error correction coded signalinto the modulated digital signal.
 8. The programmable video encodingsystem of claim 5, further comprising a record head operatively coupledto the channel coding and modulation circuit to receive the modulateddigital signal and configured to record the modulated digital signal ona recordable digital information storage medium.
 9. A programmabledigital audio recording system comprising: a read head configured toread an audio encoding algorithm from a read-only sector on a recordabledigital information storage medium; an audio encoder operatively coupledto the read head to receive and store the audio encoding algorithm,wherein the audio encoder is configured to receive an audio signal, andwherein the audio encoder is configured to execute the audio encodingalgorithm on the received audio signal to produce an encoded digitalaudio signal; a channel coding and modulation circuit operativelycoupled to receive the encoded digital audio signal and configured toconvert the encoded digital audio signal into a modulated digitalsignal; and a record head operatively coupled to the channel coding andmodulation circuit to receive the modulated digital signal andconfigured to record the modulated digital signal on the recordabledigital information storage medium.
 10. The programmable digital audiorecording system of claim 9, wherein the audio encoder includes: aninstruction memory coupled to receive and store the audio encodingalgorithm; an audio buffer coupled to receive and store the audiosignal; and a CPU coupled to the instruction memory to retrieveinstructions and coupled to the audio buffer to retrieve the audiosignal, wherein the CPU is configured to execute the audio encodingalgorithm on the audio signal.
 11. The programmable digital audiorecording system of claim 9, wherein the system is configured to readand execute the audio encoding algorithm from the read-only sector ofthe recordable digital information storage medium every time therecordable digital information storage medium is configured in anoperative relationship with the read and record heads.
 12. Theprogrammable digital audio recording system of claim 9, wherein thechannel coding and modulation circuit includes: an error correctionencoder coupled to receive the encoded digital audio signal andconfigured to convert the encoded digital audio signal to an errorcorrection coded signal; and a modulator coupled to the error correctionencoder to receive the error correction coded signal, wherein themodulator is configured to convert the error correction coded signalinto the modulated digital signal.